Strong-Field and Ultrafast Processes

点击翻译按钮获取中文摘要

This project aims to describe the interaction of intense coherent radiation with large quantum systems, and to image and control the correlated dynamical electronic processes in atoms by using ultrafast external fields. The challenge in the theoretical description of such processes resides in the difficulty in describing accurately the time-dependent interactions between particles including the strong oscillatory fields. The basic research supported by this project will provide insights into photochemical processes and contribute broadly towards efforts to control matter on an atomic scale. A postdoctoral researcher involved with this project will be given a broad education in theoretical atomic, molecular, and optical physics, in computational physics, and in ultra-cold atom physics; first-hand experience in all aspects of scientific communication, and in teaching undergraduates at a large Big 10 Land Grant university. In addition, this work will contribute to broadening participation in STEM education since the PI, an underrepresented minority, will serve as a role model for students from underrepresented groups.The time-dependent studies in strong-field physics will promote the understanding of nonlinear and correlated elementary processes, such as non-sequential double ionization (NSDI) and above-threshold ionization (ATI) of two-active-electron atomic systems. Specific investigations supported in this project include a full control of a particular channel in NSDI of He atoms by tuning parameters of the time-delayed IR and XUV fields. Control of photoelectron wave packets leading to spiral vortices from ATI demonstrates its coherence (wave) nature, which is expected to occur in several branches of science, is illustrated here in cold-atom physics. By emulating the basic pattern of spiral vortices in ultracold-atom physics, this research seeks to establish ultracold-atom quantum simulators as a complementary tool for investigating ultrafast dynamics not only for small but also for larger quantum systems. To overcome the challenge described above, this program aims to develop some theoretical time-dependent approaches (that go beyond the single-active-electron approximation). In particular, for two-electron systems the group has developed efficient, optimized, and accurate numerical methods to solve the full-dimensional time-dependent Schrödinger equation. For larger quantum systems, they propose to use ultracold-atom quantum simulators, which will be illustrated here for the case of one- and two-electron atoms as proof-of-principle calculations. The recent experimental development by David Weld from UCSB highlighted the critical need for and timeliness of this project.This project is jointly funded by the Atomic, Molecular, and Optical Physics Theory Program and the Established Program to Stimulate Competitive Research (EPSCoR).This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.